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  • Thank you very much.

  • Well, I would like to start with testicles.

  • (Laughter)

  • Men who sleep five hours a night

  • have significantly smaller testicles than those who sleep seven hours or more.

  • (Laughter)

  • In addition, men who routinely sleep just four to five hours a night

  • will have a level of testosterone

  • which is that of someone 10 years their senior.

  • So a lack of sleep will age a man by a decade

  • in terms of that critical aspect of wellness.

  • And we see equivalent impairments in female reproductive health

  • caused by a lack of sleep.

  • This is the best news that I have for you today.

  • (Laughter)

  • From this point, it may only get worse.

  • Not only will I tell you about the wonderfully good things

  • that happen when you get sleep,

  • but the alarmingly bad things that happen when you don't get enough,

  • both for your brain and for your body.

  • Let me start with the brain

  • and the functions of learning and memory,

  • because what we've discovered over the past 10 or so years

  • is that you need sleep after learning

  • to essentially hit the save button on those new memories

  • so that you don't forget.

  • But recently, we discovered that you also need sleep before learning

  • to actually prepare your brain,

  • almost like a dry sponge

  • ready to initially soak up new information.

  • And without sleep, the memory circuits of the brain

  • essentially become waterlogged, as it were,

  • and you can't absorb new memories.

  • So let me show you the data.

  • Here in this study, we decided to test the hypothesis

  • that pulling the all-nighter was a good idea.

  • So we took a group of individuals

  • and we assigned them to one of two experimental groups:

  • a sleep group and a sleep deprivation group.

  • Now the sleep group, they're going to get a full eight hours of slumber,

  • but the deprivation group, we're going to keep them awake

  • in the laboratory, under full supervision.

  • There's no naps or caffeine, by the way, so it's miserable for everyone involved.

  • And then the next day,

  • we're going to place those participants inside an MRI scanner

  • and we're going to have them try and learn a whole list of new facts

  • as we're taking snapshots of brain activity.

  • And then we're going to test them

  • to see how effective that learning has been.

  • And that's what you're looking at here on the vertical axis.

  • And when you put those two groups head to head,

  • what you find is a quite significant, 40-percent deficit

  • in the ability of the brain to make new memories without sleep.

  • I think this should be concerning,

  • considering what we know is happening to sleep

  • in our education populations right now.

  • In fact, to put that in context,

  • it would be the difference in a child acing an exam

  • versus failing it miserably -- 40 percent.

  • And we've gone on to discover what goes wrong within your brain

  • to produce these types of learning disabilities.

  • And there's a structure that sits

  • on the left and the right side of your brain, called the hippocampus.

  • And you can think of the hippocampus

  • almost like the informational inbox of your brain.

  • It's very good at receiving new memory files

  • and then holding on to them.

  • And when you look at this structure

  • in those people who'd had a full night of sleep,

  • we saw lots of healthy learning-related activity.

  • Yet in those people who were sleep-deprived,

  • we actually couldn't find any significant signal whatsoever.

  • So it's almost as though sleep deprivation had shut down your memory inbox,

  • and any new incoming files -- they were just being bounced.

  • You couldn't effectively commit new experiences to memory.

  • So that's the bad that can happen if I were to take sleep away from you,

  • but let me just come back to that control group for a second.

  • Do you remember those folks that got a full eight hours of sleep?

  • Well, we can ask a very different question:

  • What is it about the physiological quality of your sleep

  • when you do get it

  • that restores and enhances your memory and learning ability

  • each and every day?

  • And by placing electrodes all over the head,

  • what we've discovered is that there are big, powerful brainwaves

  • that happen during the very deepest stages of sleep

  • that have riding on top of them

  • these spectacular bursts of electrical activity

  • that we call sleep spindles.

  • And it's the combined quality of these deep-sleep brainwaves

  • that acts like a file-transfer mechanism at night,

  • shifting memories from a short-term vulnerable reservoir

  • to a more permanent long-term storage site within the brain,

  • and therefore protecting them, making them safe.

  • And it is important that we understand

  • what during sleep actually transacts these memory benefits,

  • because there are real medical and societal implications.

  • And let me just tell you about one area

  • that we've moved this work out into, clinically,

  • which is the context of aging and dementia.

  • Because it's of course no secret that, as we get older,

  • our learning and memory abilities begin to fade and decline.

  • But what we've also discovered

  • is that a physiological signature of aging is that your sleep gets worse,

  • especially that deep quality of sleep that I was just discussing.

  • And only last year, we finally published evidence

  • that these two things, they're not simply co-occurring,

  • they are significantly interrelated.

  • And it suggests that the disruption of deep sleep

  • is an underappreciated factor

  • that is contributing to cognitive decline or memory decline

  • in aging, and most recently we've discovered,

  • in Alzheimer's disease as well.

  • Now, I know this is remarkably depressing news.

  • It's in the mail. It's coming at you.

  • But there's a potential silver lining here.

  • Unlike many of the other factors that we know are associated with aging,

  • for example changes in the physical structure of the brain,

  • that's fiendishly difficult to treat.

  • But that sleep is a missing piece in the explanatory puzzle

  • of aging and Alzheimer's is exciting

  • because we may be able to do something about it.

  • And one way that we are approaching this at my sleep center

  • is not by using sleeping pills, by the way.

  • Unfortunately, they are blunt instruments that do not produce naturalistic sleep.

  • Instead, we're actually developing a method based on this.

  • It's called direct current brain stimulation.

  • You insert a small amount of voltage into the brain,

  • so small you typically don't feel it,

  • but it has a measurable impact.

  • Now if you apply this stimulation during sleep in young, healthy adults,

  • as if you're sort of singing in time with those deep-sleep brainwaves,

  • not only can you amplify the size of those deep-sleep brainwaves,

  • but in doing so, we can almost double the amount of memory benefit

  • that you get from sleep.

  • The question now is whether we can translate

  • this same affordable, potentially portable piece of technology

  • into older adults and those with dementia.

  • Can we restore back some healthy quality of deep sleep,

  • and in doing so, can we salvage aspects of their learning

  • and memory function?

  • That is my real hope now.

  • That's one of our moon-shot goals, as it were.

  • So that's an example of sleep for your brain,

  • but sleep is just as essential for your body.

  • We've already spoken about sleep loss and your reproductive system.

  • Or I could tell you about sleep loss and your cardiovascular system,

  • and that all it takes is one hour.

  • Because there is a global experiment performed on 1.6 billion people

  • across 70 countries twice a year,

  • and it's called daylight saving time.

  • Now, in the spring, when we lose one hour of sleep,

  • we see a subsequent 24-percent increase in heart attacks that following day.

  • In the autumn, when we gain an hour of sleep,

  • we see a 21-percent reduction in heart attacks.

  • Isn't that incredible?

  • And you see exactly the same profile for car crashes, road traffic accidents,

  • even suicide rates.

  • But as a deeper dive, I want to focus on this:

  • sleep loss and your immune system.

  • And here, I'll introduce these delightful blue elements in the image.

  • They are called natural killer cells,

  • and you can think of natural killer cells almost like the secret service agents

  • of your immune system.

  • They are very good at identifying dangerous, unwanted elements

  • and eliminating them.

  • In fact, what they're doing here is destroying a cancerous tumor mass.

  • So what you wish for is a virile set of these immune assassins

  • at all times,

  • and tragically, that's what you don't have if you're not sleeping enough.

  • So here in this experiment,

  • you're not going to have your sleep deprived for an entire night,

  • you're simply going to have your sleep restricted to four hours

  • for one single night,

  • and then we're going to look to see what's the percent reduction

  • in immune cell activity that you suffer.

  • And it's not small -- it's not 10 percent,

  • it's not 20 percent.

  • There was a 70-percent drop in natural killer cell activity.

  • That's a concerning state of immune deficiency,

  • and you can perhaps understand why we're now finding

  • significant links between short sleep duration

  • and your risk for the development of numerous forms of cancer.

  • Currently, that list includes cancer of the bowel,

  • cancer of the prostate and cancer of the breast.

  • In fact, the link between a lack of sleep and cancer is now so strong

  • that the World Health Organization

  • has classified any form of nighttime shift work

  • as a probable carcinogen,

  • because of a disruption of your sleep-wake rhythms.

  • So you may have heard of that old maxim

  • that you can sleep when you're dead.

  • Well, I'm being quite serious now --

  • it is mortally unwise advice.

  • We know this from epidemiological studies across millions of individuals.

  • There's a simple truth:

  • the shorter your sleep, the shorter your life.

  • Short sleep predicts all-cause mortality.

  • And if increasing your risk for the development of cancer

  • or even Alzheimer's disease

  • were not sufficiently disquieting,

  • we have since discovered that a lack of sleep will even erode

  • the very fabric of biological life itself,

  • your DNA genetic code.

  • So here in this study, they took a group of healthy adults

  • and they limited them to six hours of sleep a night

  • for one week,

  • and then they measured the change in their gene activity profile

  • relative to when those same individuals

  • were getting a full eight hours of sleep a night.

  • And there were two critical findings.

  • First, a sizable and significant 711 genes

  • were distorted in their activity,

  • caused by a lack of sleep.

  • The second result was that about half of those genes

  • were actually increased in their activity.

  • The other half were decreased.

  • Now those genes that were switched off by a lack of sleep

  • were genes associated with your immune system,

  • so once again, you can see that immune deficiency.

  • In contrast, those genes that were actually upregulated

  • or increased by way of a lack of sleep,

  • were genes associated with the promotion of tumors,

  • genes associated with long-term chronic inflammation within the body,

  • and genes associated with stress,

  • and, as a consequence, cardiovascular disease.

  • There is simply no aspect of your wellness

  • that can retreat at the sign of sleep deprivation

  • and get away unscathed.

  • It's rather like a broken water pipe in your home.

  • Sleep loss will leak down into every nook and cranny

  • of your physiology,

  • even tampering with the very DNA nucleic alphabet

  • that spells out your daily health narrative.

  • And at this point, you may be thinking,

  • "Oh my goodness, how do I start to get better sleep?

  • What are you tips for good sleep?"

  • Well, beyond avoiding the damaging and harmful impact

  • of alcohol and caffeine on sleep,

  • and if you're struggling with sleep at night,

  • avoiding naps during the day,

  • I have two pieces of advice for you.

  • The first is regularity.

  • Go to bed at the same time, wake up at the same time,

  • no matter whether it's the weekday or the weekend.

  • Regularity is king,